Add EasyEffects module and enable it across hosts

Add new home module for EasyEffects and include it in the default home
modules
list. Enable EasyEffects in Desktop, Laptop, and default host
configurations.
Update flake.lock entries to newer revisions. Adjust Garand‑Laptop
hardware.nix to nest hardware settings.

hosts/default/home-modules.nix

@@ -18,6 +18,7 @@ _: {
   System utilities
   */
   btop.enable = true; # Btop: a resource monitor for the terminal
+  easyeffects.enable = true; # EasyEffects: Audio effects for PipeWire applications
   cava.enable = false; # Cava: terminal audio visualizer
   fastfetch.enable = true; # Fastfetch: a fast system information tool